gamma-ray bursts and cosmology - univerzita...

Gamma-Ray Bursts and Cosmology

Attila Meszaros

Astronomical Institute, Charles University, Prague

Praha TAU listopad 2015 - leden 2016

Attila Meszaros Gamma-Ray Bursts and Cosmology

Ctyri temata (pet?)

Dejepis (historie) pro ”gamma-ray burst” (GRB)- cesky?

Prehled pozorovacıch dat

Modely

Vlastnı ”snazenı”: 2 nebo 3 podskupiny u GRBa kosmologie

Skupina v Ondrejove ???? (Rene Hudec a spol.)


The key members of the team

Zsolt Bagoly, Eotvos Univ., Budapest, Hungary

Lajos Balazs, Konkoly Observatory, Budapest,Hungary

Istvan Horvath, Zrınyi Univ., Budapest,Hungary

Attila Meszaros, Charles Univ., Prague, CzechRepublic

Peter Meszaros, Penn State Univ., StateCollege, USA

Jakub Rıpa, Taiwan University, Taipei, Tajvan

Peter Veres, Huntsville, NASA, USAAttila Meszaros Gamma-Ray Bursts and Cosmology

Figure: The magnificent seven!


Some other collaborators - occasionallycaptured

David Huja, Charles Univ., Prague, Czech Rep.

Sylvio Klose, Tautenburg Observatory,Germany

Stefan Larsson, Stockholm Univ., Sweden

Il H. Park, Sungkyunkwan Univ., Seoul, Korea

Felix Ryde, Stockholm Univ., Sweden

Dora Szecsi, Eotvos Univ., Budapest, Hungary

Jirı Stocek, Charles Univ., Prague, Czech Rep.

Roland Vavrek, Konkoly Observatory,Budapest, Hungary


A survey of the gamma-ray burst (GRB) topic

Discovery: 1967-1973 - Vela military satellitesSince 1973 - many other X-ray satellites(Pioneer-Venus, Compton, BeppoSAX,...)Total number of all discovered GRBs: cca 8000Typical energy range od photons: 20 keV − 1 MeVDurations: 0.1 s − 1000 sPeak fluxes: 0.2− 50 photons/(cm2s)Fluences: 10−8 − 10−4 erg/cm2

The cosmological origin is doubtless (since 1997)Redshifts (z): 0.0085− 8.2There are different types of GRBs (since eighties)


Figure: Typical light curves


Figure: BATSE on Compton 1990-2000 - data publicly available


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Figure: Two subgroups of the BATSE’s GRBs separated withrespect to the duration and hardness. T90 is in seconds.


2 subgroups of GRBs - an observational proof

Since eighties = two different types od GRBs (shortand long ones) - astrophysically differentphenomenaSeparation with respect to durations and”hardnesses”Hardness: (fluence at a higher energychannel)/(fluence at a softer energy channel)Separation at different satellite databases


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Figure: Sky distribution of the BATSE’s GRBs


AZ SEM JSME SE DOSTALI DNE 11.11.2015


1997 - The Year of BeppoSAX!

The first directly measuered redshift for970228z = 0, 695 1997 February - 2000 JuneBeppoSAX & BATSE simultaneously - 9 BATSEGRBs have direct redshifts


Figure: BeppoSAX


Figure: Discovery of the optical afterglow - error circle


Figure: Discovery of the optical afterglow


Figure: Dosvit-ilustrace


TROCHU O MODELECH


Figure: Dva druhy GRB - modely


Figure: Long GRB - SN connection


Figure: Long GRB - SN connection - illustration of the SNexplosion.


Figure: Formation of the short GRB - illustration of themerging.


AZ SEM JSME SE DOSTALI DNE 18.11.2015


PREHLED VLASTNI SNAHY (”SEDM STATECNYCH ASPOL.”):1. Radialnı rozdelenı GRB - jak pro kratke tak pro dlouhe =rozdelenı v rudych posuvech2. Tretı podskupina?3. Prıcne rozdelenı na obloze → plasnost kosmologickeho principu


Three important satellites - their data used byus:

BATSE instruments on the Compton Gamma-RayObservatory (1991 - 2000)BATSE = Burst And Transient Source ExperimentRHESSI (2002 -)RHESSI = Ramaty High Energy Solar SpectroscopicImagerSwift (2004 -) - the name of a fast flying bird


Figure: BATSE on Compton 1990-2000 - data publicly available


Figure: The Swift satellite - data publicly available


Figure: The RHESSI satellite - data analysis done mainly by J.Rıpa


VYSLEDEK VLASTNI SNAHY:1. Radialnı rozdelenı GRB - jak pro kratke tak pro dlouhe =rozdelenı v rudych posuvech (v z-tech)1994-96 - GRB nejen, ze jsou v kosmologickych vzalenostech, alejsou vubec nejvzdalenejsımi objekty ve Vesmıru: → jsou az doz = 20 - tri ApJ clanky dvou Meszarosu.


VYSLEDEK VLASTNI SNAHY:2. Tretı podskupina: Detaily nasledujı


3 subgroups of GRBs? Some observationalevidences

Since 1998 = also a third intermediatesubgroup; Horvath 1998; Mukherjee et al.1998 - simultaneous ApJ papersSeparation again with respect to durations and”hardnesses”Separation again at different satellite databases

Many statistical articles of the team in this topicsince 1998


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Figure: Three (?) subgroups of the BATSE’s GRBs separatedwith respect to the duration and hardness. T90 is in seconds.


Figure: The three subgroups of the RHESSI’s GRBs. T90 is inseconds.


Figure: The similar three subgroups of the Swift’s GRBs. T90is in seconds.


Intermediate subgroup: It exists, but...!

From the observational point of view:Statistical tests confirm its existence!But, carefully: This can still be a consequenceof some selection effects, biases, etc...The intermediate subgroup need not bean astrophysically different GRB class

Simply: Carefully with the physical meaning!


Astrophysics of the third subgroup - year 2015

Intermediate GRBs: Physical meaning - a keystepVeres P., Bagoly Z., Horvath I., Meszaros A., BalazsL.G. ApJ, 725, 1955 (2010)Intermediate subgroup in the Swift database =X-Ray Flashes (XRFs)→ X-Ray Flashes (XRFs) = in essence long burstsConclusion for Swift: Intermediate bursts are notastrophysically different phenomena; → they are inessence long GRBs.


Intermediate GRBs - year 2011-15

Intermediate GRBs - Physical meaning for RHESSIdata:Is it the same as for Swift? No, it is not!Rıpa J., Meszaros A., Veres P., Park I.H., ApJ,2012, 756, 44Rıpa J., Meszaros A. in preparationIntermediate subgroup in the RHESSIdatabase 6= X-Ray Flashes (XRFs)!Intermediate subgroup in the RHESSIdatabase is similar to short bursts!No relation to the long bursts!!!


Intermediate GRBs - year 2011-15

Intermediate GRBs - Physical meaning for BATSE:Is it the same as for Swift? Or as for RHESSI?Rıpa J., Meszaros A. in preparationIntermediate subgroup in the BATSEdatabase = X-Ray Flashes (XRFs) cannothold for the whole intermediate subgroup.The indentity can be fulfilled only partly.


VYSLEDEK VLASTNI SNAHY:3. Prıcne rozdelenı na obloze → plasnost kosmologickeho principu:Detaily nasledujı


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Figure: Sky distribution of the BATSE’s GRBs: No isotropy!Balazs, Meszaros A., Horvath, AA, 339, 1, 1998


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Figure: Celestial distribution of the short BATSE’s GRBs. ShortGRBs are not distributed isotropically (Vavrek et al. 2008).


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Figure: Celestial distribution of the intermediate BATSE’sGRBs. No isotropy! (Meszaros A. et al. 2000).


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Figure: Celestial distribution of the long BATSE’s GRBs; noclear result (Meszaros A. & Stocek 2003; Vavrek et al. 2008).


Impact of these discoveries on the cosmology:1. Short GRBs are different phenomena and aredistributed anistropically: in redshifts - where theydominantly are - the cosmological principle need notbe fulfilled.2. If the intermediate GRBs are in average at thesame - or even at higher redshifts - this confirmspoint No.1.3. Generally: The cosmological principle is inserious doubt! First claimed this in: MeszarosA. et al.: Baltic Astronomy, 16, 293, 2009;Meszaros A. et al.: AIP Conf.Proc., Vol.1133, 483, 2009


Cosmological principle= the Universe is spatially homogeneous andisotropic in average on large enough scales= there exists a maximal structure (”the largeenough scale”) smaller than the size of Universe.


Two cardinal questions:

1. Where are the BATSE’s short andintermediate GRBs dominantly?

2. What is the biggest observed structure in theUniverse?


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Figure: Known redshifts of the Swift’s GRBs. The intermediateGRBs are even at higher redshifts than the short ones. Butthese are Swift’s data - not the BATSE’s data: → some careis needed.


Answer to Question 1.: The short and intermediateBATSE’s GRBs should be till z ∼ (1− 2); the longones till z ∼ (10− 20). Some care is still needed -because the redshifts are indirect values.Answer to Question No.2.:

A. Up to z ' 0.1 bold inhomogeneities - manyobservational proofs.

B. Also for 1.0 > z > 0.1 inhomogeneitiesshould exist - not only in the GRB topic: Birch,Nature, 1982, 298, 451; Kashlinsky et al. ApJ,2008, 686, L49.

C. Recently a huge structure of size of Gpc wasfound around z ' 2; Horvath et al., AA, 561,L12, 2014.


SummaryThere are at least two different GRB subgroupsThe short/hard and long/soft GRBs are different objectsIntermediate GRBs: the team claims permanently thattheir existence is real - at least statisticallySwift’s intermediate GRBs = long bursts; → they are notastrophysically different objectsRHESSI’s intermediate GRBs = no relation to the longbursts; they remember the short onesBATSE’s intermediate GRBs = no clear result yetIntermediate and short BATSE’s GRBs: distributedanisotropically on the sky → impact on the cosmology!The celestial distribution of the long BATSE’s GRBs:probably also anisotropic (not proven yet obviously)The high redshifts and the anisotropies cause hugestructures in the Universe: → does thecosmological principle still hold?


Summing up the open questions:

The physics of the short subgroup is a fully openproblem!The question of the intermediate subgroup is a fullyopen problem!The impact on the cosmology is a fully openproblem!Challenge to the observers: To detect an orphanafterglow!

Danke fur die Aufmerksamkeit! Spasibo zavnimanije! Koszonom a figyelmet! Dekuji za

pozornost! Thanks for attention!


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